The overall goal of the proposed research is to better understand the diabetic regulation of vascular smooth muscle cell (VSMC) phenotype. It is clear that restenosis in diabetic patients is associated with exaggerated VSMC growth. The specific objective is to determine the in vitro effects of diabetic restenotic patients' sera, and the in vivo effects of diabetes on VSMC differentiation protein(s) expression, and migratory/proliferative signals. Recent studies have shown that atherectomy specimens from angioplasty patients, injured human saphenous vein, and streptozotocin-diabetic rat VSMC exhibit decreased expression of differentiation proteins, including SM alpha-actin, or smoothelin, leading to increased VSMC growth. Neointimal growth is associated with VSMC activation of key growth signals [extracellular signal-regulated kinases, ERK1/2; focal adhesion kinase, FAK; PI3K/Akt; and mammalian target of rapamycin, mTOR]. Rapamycin (mTOR inhibitor) inhibition of VSMC growth increases contractile phenotype. Preliminary studies reveal that restenotic patients' sera stimulate VSMC proliferation to a greater extent than PDGF. Transfection of VSMC with target-specific siRNA(s) down-regulates specific growth/insulin signaling. Together, these findings lead to the hypothesis that diabetic accentuation of VSMC dedifferentiation leads to exaggerated VSMC growth in the arterial wall. Specific Aim 1 will determine the effects of restenotic patients' sera (diabetic vs nondiabetic) on VSMC differentiation protein expression, and migratory/proliferative signaling. Specific Aim 2 will examine the diabetic regulation of human arterial phenotype and the associated alterations in the balance between arterial/VSMC differentiation protein(s) expression and key growth signaling. These studies will investigate the integrated roles of key 'growth signal transducing/differentiation proteins (proteome)' toward diabetic regulation of VSMC phenotype, and will provide novel approaches for rational therapeutic targeting to prevent enhanced restenosis/coronary grafting failure in diabetic patients.